From mboxrd@z Thu Jan 1 00:00:00 1970 From: dianders@chromium.org (Doug Anderson) Date: Mon, 8 Sep 2014 08:58:33 -0700 Subject: Unable to boot mainline on snow chromebook since 3.15 In-Reply-To: References: <20140905115704.GO13515@arm.com> <20140905122232.GP13515@arm.com> <540C202E.2060009@collabora.co.uk> <540C7F5B.6070307@gmail.com> <540C83DE.10505@collabora.co.uk> <540C8577.2070907@gmail.com> <20140908112112.GK26030@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Grant, On Mon, Sep 8, 2014 at 5:20 AM, Grant Likely wrote: > On Mon, Sep 8, 2014 at 12:21 PM, Will Deacon wrote: >> On Sun, Sep 07, 2014 at 05:19:03PM +0100, Tomasz Figa wrote: >>> At least for next 3.17-rc I'd suggest fixing this up in respective clock >>> driver and dropping the hack only after Exynos DRM patches are merged >>> and confirmed working. >> >> Whilst I'm sympathetic to people working to enable DRM, I think this is >> the right solution to the problem. The transition from simplefb to DRM >> shouldn't break display for a bunch of kernel revisions whilst the code is >> in flux. > > I would go further. The kernel behaviour has changed, and we have to > deal with platforms that assume the old behaviour. That means either > defaulting to leaving enabled regulators/clocks alone unless there is > a flag in the DT saying they can be power managed, or black listing > platforms that are known to depend on the regulator being on. > > Updating the device tree must not be required to get the kernel to > boot, but it is valid to require a DT upgrade to get better > performance (battery life) out of the platform. In this case people using SImple FB are not really using an officially sanctioned device tree. The simple-fb fragment is created on the fly via a "DO NOT SUBMIT" patch sitting on a code review server. It's not something that's shipped with real firmware nor is it something present in the kernel. See as I mentioned above. Is this really a device tree that we need to guarantee backward compatibility with? -Doug